Update opencv codec to more recent cvSaveImage prototype.

git-svn-id: file:///srv/caca.zoy.org/var/lib/svn/libpipi/trunk@4693 92316355-f0b4-4df1-b90c-862c8a59935f

pipi/codec/opencv.c

@@ -92,7 +92,7 @@ int pipi_save_opencv(pipi_image_t *img, const char *name)
     }
 
     pipi_set_colorspace(img, img->codec_format);
-    cvSaveImage(name, img->codec_priv);
+    cvSaveImage(name, img->codec_priv, NULL);
 
     return 0;
 }